Array antenna receiving device

ABSTRACT

An array antenna receiving device which compensates a phase deviation to perform an efficient beam forming while keeping phase difference information between receivers determined by the arrival direction of a user signal in a communication area to which an antenna element is directive and the array of antenna elements in a radio base station. An analog beam former provides a composite beam so that a phase difference between adjacent beams may have a fixed value determined by beams to be selected. A phase compensator provides digital signals of receivers with phase correction quantities based on any one of the digital signals so that phase differences between the antenna elements may have a fixed value.

BACKGROUD OF THE INVENTION Field of the Invention

The present invention relates to an array antenna receiving device, andin particular to an array antenna receiving device such as a multibeamantenna or, an adaptive array antenna receiving device in which aplurality of antenna elements arrayed in parallel in a radio basestation of a cellular mobile communication system and received signalsare converted into digital signals, which are provided with apredetermined amplitude and phase rotation by operations to form adesirable composite beam pattern.

The applications of the multi-beam antenna or the adaptive array antennareceiving device which use digital signal processing in the radio basestation of the cellular mobile communication system enable an enhancedgain followed by the beam pattern being equivalently focused. Further,these applications also increase the number of users accommodated in asingle cell or sector followed by the reduction of interferences withina communication area due to the directivity.

However, the realization of the array antenna receiving device withsignal processing in a digital domain requires a nonlinear device suchas a low noise amplifier (LNA) and mixers for a frequency conversion.These devices are required for the receivers respectively which convertthe received signals at the antenna elements into base band signals.This may cause a phase deviation between the receivers, which couldprevent an efficient beam to be formed and incur characteristicdeterioration.

Furthermore, since each of the receivers has a phase difference withrespect to one another, which is determined by the arrival direction ofa user signal in a communication area (cell or sector) to which theantenna element and the array of antenna elements are directed at, it isnecessary to correct or compensate only the phase deviation whilemaintaining the phase difference information between the receivers,which is required for the composite or synthetic process of the receivedsignals at the antenna elements.

For the phase correction performed during beam forming in a prior artarray antenna receiving device, a method such as performing acalibration between the receivers periodically, e.g. once a day, isrequired. However, this method is no more than beam forming in anindefinite phase condition upon the occurrence of a dynamic phasedeviation, which leads to low reliability of the device.

On the other hand, there is a view that the array antenna receivingdevice adopting an adaptive processing method does not have asubstantial phase deviation between the receivers, if any, since theamplitude and phase including the phase deviation are controlled.However, a slow convergence rate in the adaptive processing, and aseparation of the phase deviation from the amount of the amplitude andphase control in the adaptive processing is required for transmissionbeam forming for the amount of the reception time controlled upontransmission.

Further, an array antenna receiving device as shown in FIG. 22 has alsobeen proposed, in which assuming that the number of array antennaelements in a single sector be “n”. Thus, radio frequency signals fromantenna elements 1 l-1 n are provided at an analog beam former 2 with acertain (fixed) amplitude and phase rotation to form a desirable antennapattern. RF signals received by such beams are converted into base bandsignals and then converted into digital signals by receivers 3 l-3 n.The outputs of the receivers 3 l-3 n are then selectively switched by aselector 9 to select the largest beam output in power, thereby avoidingphase deviation between the receivers.

However, the prior art array antenna receiving device shown in FIG. 22does not perform adaptive beam forming in the digital domain at a latterstage of the device (not shown) so that further characteristicimprovements are not obtained. Therefore, without any phase correctionby some means, an array antenna receiving device with higher reliabilityand better performance is not realized, resulting in a problem that anadaptive array antenna or the like is not applicable to a radio basestation.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to provide an arrayantenna receiving device that compensates a phase deviation to enableefficient beam forming while maintaining phase difference informationbetween receivers using the arrival direction of a user signal in acommunication area to which an antenna element and the array of antennaelements in a radio base station is directed.

These and other objects are made by an array antenna receiving deviceaccording to the present invention arranged such that an analog beamformer makes a composite beam so that a phase difference betweenadjacent beams have a fixed value determined by the beams selected.Further, a phase compensator provides digital signals from receiverswith phase correction quantities based on any one of the digital signalsso that phase differences between the antenna elements have the fixedvalue. Namely, it is arranged so that a phase deviation of an activecircuit portion (receiver) is compensated by using inter-antenna branchphase information of a passive circuit portion such as antenna or analogbeam former without any phase deviation. Thus, it becomes possible toperform beam forming, which is higher in adaptive processing reliabilityand efficiency due to the signals produced after the phase compensation.This contributes to a realization of a multi-beam antenna, or anadaptive array antenna receiving device in the digital domain.

Also, the beam former may comprise power distribution circuits and phaseshifters.

Furthermore, the array antenna receiving device according to the presentinvention also maintains a generator for generating an uplink pilotsignal forming a reference for any direction in a communication area. Inthis case, the phase compensator converts the uplink signal into thedigital signals provided with the phase correction quantities.

Alternatively, the array antenna receiving device according to thepresent invention also may include a generator for generating an uplinkpilot signal to distribute output signals of the generator to receivingroutes. In this case, the phase compensator uses the uplink signal asreceiving signals between the antenna elements and the beam former withthe fixed phase difference to generate the digital signals provided withthe phase correction quantities.

The array antenna receiving device according to the present inventionmay also include an inverter circuit that performs an operation inverseto the beam former so that output signals of the phase compensator maybe equivalent to the receiving signals per a single antenna element; andan adaptive processing portion that combines output signals of theinverter circuit to form the adaptive antenna pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are block diagrams showing arrangements of an arrayantenna receiving device according to the present invention;

FIG. 2 is a block diagram showing an example of a 4×4 analog beam formerused in an array antenna receiving device according to the presentinvention;

FIG. 3 is a graph showing a radiation characteristic of a 4×4 analogbeam former used in an array antenna receiving device according to thepresent invention;

FIG. 4 is a graph showing a phase characteristic of a 4×4 analog beamformer used in an array antenna receiving device according to thepresent invention;

FIG. 5 is a block diagram showing an example of an 8×8 analog beamformer used in an array antenna receiving device according to thepresent invention;

FIG. 6 is a graph showing a radiation characteristic of an 8×8 analogbeam former used in an array antenna receiving device according to thepresent invention;

FIG. 7 is a graph showing a phase characteristic of an 8×8 analog beamformer used in an array antenna receiving device according to thepresent invention;

FIG. 8 is a diagram illustrating a linear array antenna used in an arrayantenna receiving device according to the present invention;

FIG. 9 is a block diagram showing an embodiment of a phase correctionarithmetic portion used in an array antenna receiving device accordingto the present invention;

FIG. 10 is a block diagram showing an embodiment of a phase deviationarithmetic portion used in an array antenna receiving device accordingto the present invention;

FIG. 11 is a block diagram showing another embodiment of a phasecorrection arithmetic portion used in an array antenna receiving deviceaccording to the present invention;

FIG. 12 is a block diagram showing an embodiment of a phase rotator usedin an array antenna receiving device according to the present invention;

FIG. 13 is a block diagram showing another embodiment of a phasedeviation arithmetic portion used in an array antenna receiving deviceaccording to the present invention;

FIG. 14 is a block diagram showing an example of an inverter circuit ofan array antenna receiving device according to the present invention;

FIG. 15 is a graph showing a radiation characteristic produced after aninversion by an inverter circuit used in an array antenna receivingdevice according to the present invention;

FIG. 16 is a graph showing a phase characteristic produced after aninversion by an inverter circuit used in an array antenna receivingdevice according to the present invention;

FIG. 17 is a block diagram showing an example of an array antennareceiving device according to the present invention wherein the invertercircuit has a through arrangement;

FIG. 18 is a plain view showing an embodiment of an analog beam formerused in an array antenna receiving device according to the presentinvention;

FIG. 19 is a circuit diagram showing an embodiment of an analog beamformer used in an array antenna receiving device according to thepresent invention;

FIGS. 20A and 20B are diagrams showing an uplink signal generatorprovided in a sector for an array antenna receiving device according tothe present invention;

FIG. 21 is a block diagram showing an embodiment of an uplink signalgenerator combined in a radio base station with an array antennareceiving device according to the present invention; and

FIG. 22 is a block diagram showing a prior art device.

Throughout the figures, like reference numerals indicate identical orcorresponding portions.

DETAILED DESCRIPTION

FIGS. 1A and 1B show arrangements of an array antenna receiving deviceaccording to the present invention. In particular, FIG. 1A shows a feedforward arrangement and FIG. 1B shows a feedback arrangement.

In FIG. 1A, antenna elements 11-1 n (hereinafter occasionally andgenerally referred to as “1”), an analog beam former 2, and receivers31-3 n (hereinafter occasionally and generally referred to as “3”) areprovided in the same manner as FIG. 22.

In FIG. 1A, radio signals received by the antenna elements 1 are inputto the beam former 2 where the radio signals are combined with aparticular weight and phase, and provided at output terminals. Eachoutput of the beam former 2 is subject to a particular amplification andfrequency conversion to produce base band signals for passing throughthe receivers 3. The receivers 3 further convert the base band signalsinto digital signals by A/D conversion.

As can be seen, the receivers 3 are connected to a phase compensator 10.As shown by dotted-lines in FIG. 1A, the phase compensator 10 is furtherconnected to an inverter circuit 6 for performing an inverse operationof the beam former 2 so that the output signals of the phase compensator10 may be equivalent to those of the antenna elements 1 except that theyare digital signals. The inverter circuit 6 is further connected to anadaptive processing portion 7 for compositing the output signals of theinverter circuit 6 to form an adaptive antenna pattern. The invertercircuit 6 may also have a through-put arrangement, where the inverter iseliminated.

The phase compensator 10 includes phase rotators 42-4 n (hereinafteroccasionally and generally referred to as “4”), which are connectedbetween the receivers 32-3 n and a phase correction (quantity)arithmetic portion 5. The phase correction arithmetic portion receivesthe output signals X1-Xn from the receivers 31-3 n to calculate phasecorrection quantities as noted below, which are supplied to the phaserotators 42-4 n. The digital signal from the receiver 31 is used as areference for the digital signals of the receivers 3.

In the array antenna receiving device of FIG. 11B, a phase compensator10 is provided between the receivers 3 and the inverter circuit 6 in thesame manner as FIG. 1A. Since this array antenna receiving device adoptsa feedback arrangement, a phase correction arithmetic portion 5 isarranged so that it receives an output signal X1 from receiver 31 andoutput signals X2-Xn from the phase rotators 42-4 n to provide phasecorrection quantities for the phase rotators 42-4 n.

FIG. 2 shows an example arrangement of the analog beam former 2 shown inFIGS. 1A and 1B, which is specifically an analog-domain beam formerknown as a “Butler Matrix” in the form of 4 (inputs)×4 (outputs). Asshown in FIG. 2, this beam former 2 includes −90° hybrid circuits211-214 (Θ), which are known as power distribution circuits forrespectively distributing one input as two outputs with a phasedifference of −90° between each other, 45° phase shifters 221, 224 (Φ1,Φ4), and 0° phase shifters 222, 223 (Φ2, Φ3). In this example, thehybrid circuit 211 receives the output signals A,C respectively from theantenna elements 11, 13 and provides one of the output signals to hybridcircuit 213 through the phase shifter 221 and the other output signal tothe hybrid circuit 214 through the phase shifter 223. The hybrid circuit212 receives the output signals B, D respectively from the antennaelements 12,14, and provides one of the output signals to the hybridcircuit 213 through the phase shifter 222 and the other output signal tothe hybrid circuit 214 through the phase shifter 224. Therefore, thehybrid circuit 213 outputs a #3 beam and #1 beam, and the hybrid circuit214 outputs a #4 beam and #2 beam, as shown in the figure.

FIG. 3 shows a radiation characteristic of the analog beam former 2 ofFIG. 2, while FIG. 4 shows a phase characteristic of the same. As shownin FIG. 3, #1-#4 beams are output in order.

In view of the beam former 2 producing such a radiation characteristicwith reference to FIG. 4, it is found that phase differences betweenadjacent beams (main lobes) have fixed values as indicated by theordinate over arrival angle regions a-c as indicated by the abscissa.

FIG. 5 shows an arrangement (2) of the analog beam former 2, which iscomposed of −90° hybrid circuits 231-242, 67.5° phase shifters 259, 266(Φ1, Φ8), 22.5° phase shifters 262, 263 (Φ4, Φ5), 45° phase shifters251,252, 256, 258 (Φ9, Φ10, Φ15, Φ16), and 0° phase shifters 260, 261,264, 265, 252, 254, 255, 257 (Φ2, Φ3, Φ6, Φ7, Φ11, Φ12, Φ13, Φ14), inthe form of 8 inputs×8 outputs.

In this example, when the output signals A-H of the antenna elements11-18 as shown in the figure are input to the analog beam former 2, a #5beam, #1 beam, #7 beam, #3 beam, #6 beam, #2 beam, #8 beam, and #4 beamare output as seen from the top of the figure. FIG. 6 shows a radiationcharacteristic of the analog beam former 2 shown in FIG. 5, in which#1-#8 beams are output in order.

FIG. 7 shows a phase characteristic of the 8×8 Butler Matrix, from whichit is shown that this analog beam former has fixed phase differencesover arrival angle regions a-g like the example in FIG. 4. Thus, thearrival angle regions and the fixed phase difference values Δθ_(nm)corresponding to the arrival angle regions in the analog beam former 2are illustrated as in the following table 1. This table is obtained,assuming that the interval of the antenna elements 1 is λ and therespective radiation pattern of the antenna elements 1 is a beam havinga half power beam width of 60°.

TABLE I (1) 4 × 4 BEAM FORMER REGION a b C ARRIVAL ANGLE (°) −22˜−8 −7˜78˜22 Δθ_(nm) (°) ±180 0 ±180 (2) 8 × 8 BEAM FORMER REGION a b C d e f gARRIVAL ANGLE (°) −25˜−19 −18˜−11 −10˜−4 −3˜3 4˜10 11˜18 19˜25 Δθ_(nm)(°) −157.5 ±180 157.5 0 −157.5 ±180 157.5

When a user's uplink signals are received at the antenna elements 1respectively with any adjacent beams, the beam former 2 will have afixed value of the phase difference between the uplink signals dependingon the combination of the adjacent beams to be selected. In other words,a composite beam will be made so that the phase difference betweenadjacent output beams obtained from the output signals of the antennaelements 1 may have a fixed value determined by the combination of theoutput beams to be selected. Therefore, the presence of a phasedeviation in a receiver system will give rise to a deviation from thefixed value.

The present invention is based in principle on this deviation beingcorrected and restored to the fixed value determined by the beams to beselected. More specifically paying attention to a single sector, andassuming that the number of users existing within the area is k and thenumber of the array antenna elements which is supposed to be a lineararray antenna as illustrated in FIG. 8 is n, the user signals receivedby the antenna elements 1 shown in FIG. 1 are combined by the beamformer 2, and then output from the receivers 3.

For example, when the uplink signal of a user “i” is received by thereceivers 3 at the same time for the #1 and #2 beams which are adjacentto each other as shown in FIG. 4, the output signals X1 and X2 are givenby the following equations.

X1=A1 ·exp [j(α_(i)(t)+Ø₁ )]  Eq.(1)

X2=A2 ·exp [j(α_(i)(t)+Δθ₁₂+Ø₂)]  Eq.(2)

where

α i (t): an arbitrary phase (i=1, 2, . . . ,k) in the beam compositeoutput of the ith user signal.

Δθ₁₂: a phase rotation, which exhibits a fixed value within a certainarrival angle region, determined by the adjacent #1 and #2 beams to benoted, assuming that X1 is a reference.

A1, A2: amplitudes of user signals at the #1 and #2 beams as selected.

Ø₁, Ø₂: phase deviations due to the receivers 31 and 32.

The following operations will be made from the output signals X1 and X2.

Y12=X2·X*1=A1·A2·exp [j(Ø₂−Ø₁+Δθ₁₂)]  Eq.(3)

The phase term in Eq.(3) is given by the following equation.

arg (YI2)=Ø₂−Ø₁+Δθ₁₂  Eq.(4)

Δθ₁₂ in Eq.(4) depends on the #1 and #2 beams to be selected, and has aknown fixed value as illustrated in the above Table 1 in any arrivalangle region. Therefore, the subtraction of the fixed value enables thephase difference D between the receivers 31 and 32 to be derived asgiven by the following equation.

Φ=Ø₂−Ø₁  Eq.(5)

With this phase difference (D for the phase correction of the signal X2as given by the following equation, the phase-corrected output Z2 can beexpressed by the following equation incorporating Eq.(2).

Z2=X2·exp[−jΦ)]=A2 exp[j(α_(i)(t)+Ø₁+Δθ₁₂)]  Eq. (6)

Meanwhile, the signal X1 is a reference signal not subject to any phasecorrection so that X1=Z1. Being compared with Eqs.(1) and (2), Eq.(6)excludes Ø₂, so that except the phase difference Δθ₁₂ determined by the#1 and #2 beams to be selected the signals Z₁ and Z₂ have a common termof exp [j(αi(t)+0 1)], which means that the phase deviation between theadjacent #1 and #2 beams has been compensated.

This operation performed in order between adjacent beams will phasecompensate for all of the receiver's routes. It is noted that the phasecorrection for any adjacent beams requires an operation in view of thelast phase correction quantity between the last adjacent beams. Thus,the phase compensator 10 outputs digital signals converted from theoutput signals of the receivers 3 and provided with a phase correctionquantity so that the phase difference between the beams may have thefixed value on the basis of the digital signals of the receivers 3.

The above-noted arithmetic portion may use a signal, e.g. a signal at anintersecting point between the #1 and #2 beams in FIG. 3. This signal ishigher in reception level as any one of the digital signals to beselected, among arrival signals, in the same direction, of beams havingadjacent directivities and being simultaneously received.

Alternatively, the arithmetic portion may use an average value ofsignals in excess of a certain level as any one of the digital signalsto be selected among arrival signals in the same direction of beamshaving adjacent directivities and being simultaneously received.

FIG. 9 shows an embodiment (1) of the phase correction arithmeticportion 5 in the feed forward-arranged phase compensator 10 used in anarray antenna receiving device according to the present invention shownin FIG. 1A. In this embodiment, the output signals X1-XN from thereceivers 31-3 n are supplied to searchers 511-51 n (generally referredto as “51”), in which valid paths of the signals are extracted on thesupposition of a CDMA (Code Division Multiple Access) system.

The output signals of the searchers 511-51 n are supplied to a selector52, in which adjacent two beams are simultaneously detected. Thisenables a higher-level signal such as simultaneously detected by the #1and #2 beams in the example of FIG. 3 is selectively output. Theselector 52 is connected to phase deviation arithmetic portions 532-53 n(generally referred to as “53”). The phase deviation arithmetic portions53 are shown in detail in FIG. 10, where the signals selected by theselector 52 are used to execute the above Eqs.(3)-(5).

The output signals of the phase deviation arithmetic portions 532-53 nare branched into two. One is forwarded to phase correction weightcalculators 542-54 n, while the other to adders 553-55 n for theaddition to the output signals of the phase deviation arithmeticportions 532-53 n in the next object beam combination.

The phase correction quantities thus determined between all of theadjacent beams are performed with a complex operation (exp.) at phasecorrection weight calculators 542-54 n (generally referred to as “54”),and then supplied to the phase rotators 42-4 n for the phase correction.

The phase deviation arithmetic portions 53 shown in FIG. 10 arerespectively composed of a multiplier 53a, a phase term calculator 53b,and a subtracter 53c. The multiplier 53a executes the above Eq.(3), thephase term calculator 53b executes Eq.(4), and the subtracter 53cremoves the fixed phase difference Δθ₁₂ from Eq.(4), whereby the phasedifference D of the receivers 31,32 given by Eq.(5) is continuouslyoutput.

FIG. 11 shows an embodiment (2) of the feedback-arranged phasecorrection arithmetic portion 5 in the array antenna receiving deviceaccording to the present invention shown in FIG. 1B. In this embodiment,searchers 51, a selector 52, phase deviation arithmetic portions 53,phase correction weight calculators 54, and adders 553-55 n (generallyreferred to as “55”) are the same as in the embodiment (1) of the phasecorrection arithmetic unit shown in FIG. 9. However, adders 562-56 n(generally referred to as “56”) are provided at the latter stage of thephase deviation arithmetic portions 53 to add the last phase correctionquantities with new phase correction quantities, respectively. Namelythe adders 56 serve to hold the last phase correction quantities bytaking advantage of the feedback-arranged phase compensation calculatingthe next phase correction quantity from the previous one.

FIG. 12 shows an embodiment of the phase rotators 4 in the array antennareceiving device according to the present invention shown in FIG. 1.Each of the phase rotators 4 include a multiplier for multiplying theoutput signals from the receivers with a phase-correction-weighted valueafter the term “exp [−jΦ]” having been performed by the phase weightcalculators 54 in either of the embodiments shown in FIGS. 1A and 1B.

FIG. 13 shows a modified example for the embodiment (1) of the phasedeviation arithmetic portions 53 shown in FIG. 10, in which anintegrator 53d and an average value calculator 53e are provided betweenthe phase term arithmetic portion 53b and the subtracter 53c, differentfrom the embodiment (1).

Namely, the selector 52 connected to this embodiment portion selects twoor more signals, which are not limited to plural different user signalsbut may be made by single user multipath signals. The phase deviationarithmetic portion 53 sums at the integrator 53d the operated resultobtained from the phase term calculator 53b in accordance with Eq.(4)and calculates the average value at the average value calculator 53e forthe subtracter 53c.

Accordingly, while the phase deviation arithmetic portion 53 in FIG. 10continuously outputs the phase deviation Φ, that in FIG. 13 equivalentlyoperates the phase difference Φ at a fixed time interval, whereby thephase correction quantities supplied to the phase weight calculators 54become more reliable in the latter portion.

FIG. 14 shows an arrangement of the array antenna receiving deviceaccording to the present invention, particularly at the latter stage ofthe phase compensator 10 shown in FIG. 1. In this arrangement, theinverter circuit 6 executes the inverse operation to the beam former 2with the signals after having been phase-corrected by the phasecompensator 10. This enables signals to be output respectivelyequivalent to the signals received by each of the antenna elements 1 tothe adaptive processing portion 7.

In other words, to the adaptive processing portion 7 the phase-correctedsignals by the phase compensator 10 which are preserved with phasedifference information determined by the arrival direction of the user 1signal and the array of the antenna elements 1 are supplied.

The output signal of the adaptive processing portion 7 after having beenperformed with certain adaptive processing is input to a demodulator(DEM) 8 to complete an adaptive array antenna arrangement. It should benoted that such adaptive processing by the adaptive processing portion 7is not limited to the above embodiments but applicable to any processingwhich receives the output signals of the antenna elements.

FIGS. 15 and 16 respectively show a radiation characteristic and a phasecharacteristic after the beam inversion at the inverter circuit 6 ofFIG. 14. As seen from FIG. 15, the radiation characteristic exhibits thesame as that of a single antenna element. It is also seen from FIG. 16that the phase differences are shown equal to each other as in the casereceived by an array antenna where a phase difference between thereceivers determined by the arrival direction of the user signals andthe array of the antenna elements is preserved.

Also, the inverter circuit may be eliminated to provide a througharrangement without any operations as shown in FIG. 17 in order for theadaptive processing portion 7 to input the output signals of the phasecompensator 10 directly, which realizes a beam-space adaptive arrayantenna arrangement.

FIG. 18 shows an embodiment of the 4×4 analog beam former 2 shown inFIG. 2. In this embodiment, the beam former 2 is composed of 3 dB90°hybrid circuits 621-624 (generally referred to as “62”) made of a microstrip line, and a phase shifter 63 adjustable with a line length on aprinted-board 61.

It is to be noted that this beam former 2 is not limited to thisstructure but as shown in FIG. 19, the 3 dB90° hybrid circuits 62 may beemployed separately, and joined in three dimensions with a coaxial line64 or the like also serving as a phase shifter. This is the same as the8×8 beam former shown in FIG. 5.

Although the above embodiments suppose a case where users existuniformly within a sector, there may be actually no such supposed state.The users may exist only in one direction within a sector in an ultimatecase, in which it is impossible to perform an appropriate phasecompensation and beam forming.

As shown in FIG. 20, a pilot signal generator u may be preliminarilyprovided in a sector 100 covered by a radio base station BS.Particularly, assuming that an antenna directed to the sector 100 asshown in FIG. 20A comprises a 4-element linear array antenna, it ispreferable to choose angles Ø1, Ø2 (=0° ), and Ø3 within the arrivalangle regions a-c in the radiation characteristic of the analog beamformer shown in FIG. 3, or to choose an angle in the vicinity of acontact between adjacent beams for arranging the received levels ifpossible. It should be noted that in this embodiment the uplink signalgenerator does not have to be strictly positioned.

Thus, at least three reference signals are required to form four beamswith four antennas. Each of the reference signals is used to calculatethe phase correction quantity in the same manner as the aboveembodiments.

FIG. 20B shows an arrival angle in a vertical plane, which needs nomodification in arrangement particularly irrespective of a value of γ.

FIG. 21 shows an embodiment incorporating an uplink pilot signalgenerator in the radio base station. Assuming that the antenna directiveto the sector 100 as shown in FIG. 20A comprises a 4-element lineararray antenna, a signal generator 71 produces more than three kinds ofuplink signals, which are distributed by distribution circuits 721-72 n(generally referred to as “72”).

Phase shifters 731-73 n (generally referred to as “73”) then establishpseudo arrived directions of the signals within the area of the arrivalangle regions a-c in FIG. 3, or an angle in the vicinity of a contactbetween adjacent beams for arranging the received levels if possible. Itis unnecessary in the present invention to set a strict arrivaldirection.

After the reference signals are combined by combiners 741-74 n(generally referred to as “74”), the combined signals are then input tocouplers 751-75 n (generally referred to as “75”) between the antennaelements 1 and the analog beam former 2. Therefore, it is possible tocalculate the phase correction quantities in the same manner as the caseof an actual user signal using those reference signals. This device canbe utilized as a standby where no user signal is obtained in apredetermined arrival angle distribution, whereby it becomes possible toimprove the reliability of the radio base station.

As described above, an array antenna receiving device according to thepresent invention is arranged such that an analog beam former makes acomposite beam so that a phase difference between adjacent beams mayhave a fixed value determined by beams to be selected. Further, a phasecompensator provides digital signals for receivers with phase correctionquantities based on any one of the digital signals so that phasedifferences between the antenna elements may have the fixed value. Inother words, it is arranged that a phase deviation of an active circuitportion (receiver) by using inter-antenna branch phase information of apassive circuit portion such as antenna and analog beam former withoutany phase deviation may be compensated. Thus, it becomes possible toperform beam forming which is higher in adaptive processing reliabilityand efficiency due to signals after the phase compensation. This largelycontributes to a realization of a multi-beam antenna, or adaptive arrayantenna receiving device in digital domain.

What is claimed is:
 1. An array antenna receiving device comprising: aplurality of antenna elements arrayed in parallel for receiving inputsignals; an analog beam former for combining the input signals intocomposite beams in such a way that phase differences between adjacentbeams have respectively fixed values determined relative to selectedoutput beam combination; a plurality of receivers which convert thecomposite beams of the beam former into digital signals; and a phasecompensator which compensates the digital signals with phase correctionquantities thereby removing, relative to any one of the digital signals,phase deviations from the respective fixed values of phase differencesin order for said digital signals to maintain said fixed values.
 2. Thearray antenna receiving device as claimed in claim 1, wherein the phasecompensator includes an arithmetic portion for multiplying the digitalsignals between adjacent beams with a difference of the fixed value todetermine the phase correction quantities and a plurality of phaserotators for phase-rotating the digital signals by the phase correctionquantities except for a reference one of the digital signals.
 3. Thearray antenna receiving device of claim 2, wherein the arithmeticportion uses a signal higher in reception level as any one of thedigital signals to be selected of beams having adjacent directivitiesand being simultaneously received.
 4. The array antenna receiving deviceof claim 2, wherein the arithmetic portion uses an average value ofsignals in excess of a predetermined level as any one of the digitalsignal to be selected of beams having adjacent directivities and beingsimultaneously received.
 5. The array antenna receiving device of claim1, wherein the phase compensator includes a plurality of phase rotatorsfor phase-rotating the digital signals of the receivers by the phasecorrection quantities except for a reference one of the digital signals,and an arithmetic portion for receiving the reference one of the digitalsignals and output signals of the phase rotators to multiply the digitalsignals between adjacent beams with a difference of the fixed value todetermine the phase correction quantities.
 6. The array antennareceiving device of claim 5, wherein the arithmetic portion uses asignal higher in reception level as any one of the digital signals to beselected of beams having adjacent directivities and being simultaneouslyreceived.
 7. The array antenna receiving device of claim 5, wherein thearithmetic portion uses an average value of signals in excess of apredetermined level as any one of the digital signal to be selected ofbeams having adjacent directivities and being simultaneously received.8. The array antenna receiving device of claims 1, wherein the beamformer comprises power distribution circuits and phase shifters.
 9. Thearray antenna receiving device of claim 1, further comprising agenerator for generating uplink pilot signals forming a reference in anydirection in a communication area, the phase compensator converting theuplink signal into the digital signals provided with the phasecorrection quantities.
 10. The array antenna receiving device of claims1, further comprising a generator for generating uplink pilot signals todistribute output signals of the generator to receiving routes, thephase compensator using the uplink signals as receiving signals betweenthe antenna elements and the beam former with the fixed phase differenceto generate the digital signals provided with the phase correctionquantities.
 11. The array antenna receiving device of claims 1, furthercomprising an inverter circuit which performs an inverse conversion ofthe beam former so that output signals of the phase compensator areequivalent to the input signals per a single antenna element; and anadaptive processing portion which combines output signals of theinverter circuit to form the adaptive antenna pattern.